1. Field of the Invention
The present invention relates to a method of fertilizing a lawn which is located at least partially in the shade, which comprises the step of applying a liquid fertilizer to the leaves of the grass plants of the lawn.
2. Description of the Prior Art
The conventional fertilization of grass plants is based on supplying to the lawn such nutrients as nitrogen, phosphate and potassium. Applying nitrogen-containing fertilizers to the grass plants supplies to the grass plants nitrogen in the form of nitrate (NO.sub.3 --) or ammonium (NH.sub.4 --). The application of phosphate- and potassium-containing fertilizers supplies to the grass plants phosphate (P.sub.2 O.sub.5) and potash (K.sub.2 O). The nutrients may be applied to the leaves or the roots of the grass plants.
Through photosynthesis, these nutrients are converted in the grass plants from an inorganic to an organic form. The inorganic form of the nutrients is the form which is poorer in energy while the organic form is richer in energy. The energy-richer forms of the nutrients, which have been converted from the energy-poorer form by photosynthesis and are called plant assimilates, are needed by the plants for the formation of leaves and roots.
At which point of the plants the assimilates are primarily needed depends, on the one hand, on the internal growth factors of the plant, i.e. their genetic make-up, and, on the other hand, on the external growth factors of the plant, i.e. the supply of water, such energy sources as light and heat, and nutrients.
It is known that lack of light will enhance the growth of grass blades while it will proportionally reduce the growth of grass roots. This is controlled by the concentration of nutrients in the grass plants, such as nitrate, and of assimilates, for example saccharose, amino acids and proteins. The higher the concentration of nutrients in the plant, the higher the plant's consumption of assimilates for forming leaves. The higher the concentration of assimilates in the plant, the higher the plant's tendency to form roots in order to absorb nutrients.
Since lawns are regularly cut, the mass of grass leaves is constantly reduced. The reduction of the mass of grass leaves correspondingly reduces the surface area of the grass leaves, which accordingly reduces the photosynthesis. This causes the absorption of light by the grass plants to be considerably limited. Under optimal soil conditions, the plants will adapt the mass of the roots to the produced rate of the assimilates of the mass of the leaves when the lawn is cut regularly.
When the lawn is located in the shade, i.e. an area relatively deprived of light, the ratio of the mass of leaves to the mass of roots is changed. The less light energy the grass leaves can absorb, the less nutrient salts, such as nitrate, may be converted by photosynthesis into plant assimilates. This results in a change of the equilibrium of nutrients and assimilates in the plants. The concentration of nutrients in the plants rises while the concentration of plant assimilates is lowered. This causes the plants to produce a larger mass of leaves to convert the high concentration of nutrients by the photosynthesis occurring in the leaves into the assimilates needed by the plants. In this process, the plants need the available assimilates for the production of the leaves while the growth or roots is neglected in proportion to the lack of light.
On the other hand, if the lawn receives a lot of light for the photosynthesis and the supply of nutrients to the grass plants is sufficient, which causes the equilibrium to change slightly in favor of the assimilates, the grass plants will use the assimilates primarily for the formation of roots.
The carrying capacity of a lawn used for sport activities, such as a baseball or football field, depends to a large extent on the root formation of the grass plants. If the root system of the lawn is weak, sport activities will rapidly damage the lawn. One reason for weak grass roots is a lack of light.
Known fertilizers and fertilization systems supply the nutrients required for photosynthesis to the roots or the blades of the grass plants.